Pyrotechnic unit



Patented Mar. 3, 1936 PATENT QFFIQ'E PYROTECI-INIC UNIT Max'W. Fischer,Washington, D. 0., and Raymond L. Graumann, Alexandria, Va.

Application October 6, 1932,-Serial No. 636,532 6 Claims. (01. 102 -24)(Granted under the act of March 3, 1883, as amended April 30, 1928; 3700. G. 757) invention relates to a pyrotechnic unit, and moreparticularly to a moisture proof closure "for such unit for use inaircraft float lights.

It is the object of this invention to provide a pyrotechnic unitthatwill be protected for an indefinite length of. time againstpenetration of moisture.

' With the above and other objects in View, the invention consists inthe construction, combination and arrangement of parts as will be morefully described hereinafter.

The-drawing shows an axial section of one embodiment of our invention.

Aircraft fioat lights are intended to be dropped into water and areprovided with wooden bodies to make them sufficiently buoyant to floaton the surface thereof. Heretofore, the pyrotechnic material in suchlights has been placed in a cavity in the wooden body but it is foundthat moisture penetrates the wood and impairs the pyrotechnic charge. Wehave devised an inclosure for such pyrotechnic material that willprotect it from moisture under any conditions of humidity and for anylength of time.

As shown in the drawing, our invention comprises an elongated metal tubeI having a closed end 2. In the open end is a base member 3 havin anexternally threaded shank 4 extending from its outer face. The edge oftube I is spun or otherwise upset over the edge of the outer face ofbase 3, as indicated at 5. A nut B is screwed on shank 4 to clamp edge 5against base 3 and form a completely water-proof closure. A kerf isformed in the inner face of closed end 2 to weaken the end so that thepressure of gases generated in the tube will readily blow out a portionof the closed end to permit the flame from the pyrotechnic material topass out into the air and become visible. The shank 4 has in it a seat 8for a primer to be fired by any of the well known mechanisms used forthis purpose and a passage 9 leading inwardly to permit the flame fromthe primer to ignite a fuse train III that is inserted into the base 3and extends upwardly through pyrotechnic pellets I I to the ignitingmixture I2 in starter cup I3. When our pyrotechnic unit is employed forthe use above mentioned, namely, aircraft float lights, the firing pm ofthe firing mechanism is driven against the primer when a portion of thatmechanism impacts the water after the light has been dropped from anaircraft. Longitudinally bored member I6 clamps a thin copper cup I'Ithat will be indented, but not punctured, by a firing pin, againstshoulder I8 0n shank 4 to prevent penetration of moisture around theprimer in chamber 8. .A disk I4 -of fiber or other combustible materialcloses the open end of starter cup I3, the edges of the cup being bentover the outer face of disk I4 in a plurality of places as indicated atI5 to retain the disk in position. 7

When the primer ignites fuse train I0, the train burns upwardly andignites the mixture in starter cup I3. The cup burns and so propagatesthe combustion to pellets Ii which burn downwardly through their length.Disk I4 also burns and the gaseous. pressure developed inside tube Iblows out that portion of end 2 included within the kerf l and sopermits the escape of flaming gases to the air to form a visible light.

The wall of tube I is thin and is made of block tin, which will melt orburn down at the same rate as the pyrotechnic pellets without affectingthe time of burning or the character of the resulting signal.

It is obvious that the edge of tube I may be secured to base 3 bysoldering or brazing, or in any manner to provide a water-tight joint.

A pyrotechnic charge inclosed as herein disclosed will be protectedagainst moisture for any length of time and consequently will alwaysmaintain its activity unless decomposition of the pyrotechnic materialoccurs due to inherent properties of its composition.

It will be understood thatthe above description and accompanying drawingcomprehend only the general and preferred embodiment of our invention,and that various changes in construction, proportion and arrangement ofparts may be made within the scope of the appended claims withoutsacrificing any of the advantages of this invention.

The invention herein described may be manufactured and used by or forthe Government of the United States for governmental purposes withoutthe payment of any royalty thereon.

We claim:

1. In a pyrotechnic unit, a base having an externally threaded shank onits outer face, said shank and base having a passage therethrough, anelongated enclosing member having one end closed and the edge of theother end upset against the outer face of said base, said closed endbeing weakened by a kerf in its inner face, a nut screwed on said shankto clamp said edge against said base, pyrotechnic material in saidenclosing member, a starter cup seated on said material at the closedend of said member, a combustible disk in the open end of said cup,portions of the edge of said cup being overturned over said disk,

and a fuse element fitted in the passage through said base, andextending through the pyrotechnic material into said cup.

2 In a pyrotechnic unit, a base having an externally threaded shank onits outer face, said shank and base having a passage therethrough anelongated enclosing member of moisture-proof material closed at one endand having the edge of the other end inturned against the outer face ofsaid base, the closed end of'said member being weakened by a kerf on itsinner face, a nut on said shank set tightly against the inturned edge ofsaid member, a starter cup in said member at its closed end, acombustible disk closing said cup, portions of the edge of said cupbeing turned over said disk, and a cup of readily puncturable metalclamped on said shank to close the outer end of the openingtherethrough.

3. A burning pyrotechnic unit comprising an enclosing member of blocktin having a closed end and an open end, a closure seated in said openend over which the edge of said member is turned, a clamping elementengaged with said closure to clamp said edge against said closurepyrotechnic material in said member and a fuse train extending into saidclosure and thence throughout the length of said material.

4. A burning pyrotechnic unit comprising an enclosing member of metaladapted to be broken down by fire at the same rate as the pyrotechnicmaterial therein burns, said member having a closed end and an open end,a closure seated in said open end over which the edge of said member isturned, a clamping element engaged with said closure to clamp said edgeagainst said closure pyrotechnic material in said member and a fusetrain extending into said closure and thence throughout the length ofsaid material.

5. A burning pyrotechnic unit comprising an enclosing member of blocktin having a closed end and an open end, an axially bored closure seatedin said open end over which the edge of said member is turned, aclamping element engaged with said closure to clamp said edge againstsaid closure, a thin walled cup of soft metal to close the bore in saidmember but readily indentable by a firing pin pyrotechnic material insaid member and a fuse train extending into said closure and thencethroughout the length of said material.

6. A burning pyrotechnic unit comprising an enclosing member of blocktin having a closed end and an open end, an axially bored closure seatedin said open end over which the edge of said member is turned, aclamping element engaged with said closure to clamp said edge againstsaid closure, a thin walled imperforate cup of soft metal to close thebore in said member, means to clamp said cup to said closure,pyrotechnic material in said member and a fuse train extending into saidclosure and thence throughout the length of said material.

MAX W. FISCHER. RAYMOND L. GRAUMANN.

